Spark plugs can be used to initiate combustion in internal combustion engines. Spark plugs typically ignite a gas, such as an air/fuel mixture, in an engine cylinder or combustion chamber by producing a spark across a spark gap defined between two or more electrodes. Ignition of the gas by the spark causes a combustion reaction in the engine cylinder that causes the power stroke of the engine. The high temperatures, high electrical voltages, rapid repetition of combustion reactions, and the presence of corrosive materials in the combustion gases can create a harsh environment in which the spark plug functions.
Spark plugs typically include one or more ground electrodes and a metal shell supporting other components of the spark plug. The ground electrodes have traditionally been attached to the metal shells via a resistance welding process. While resistance welding has worked, sometimes welded material gets extruded laterally as the ground electrodes and shells are melted and pressed together. The extruded material might then require removal in a downstream metalworking process—this is sometimes referred to as weld flash removal. This may be especially true when certain nickel-based alloys are involved like those that go by the name Inconel® 601.